I'll skip the format because this isn't for a course, just a textbook I'm reading. Also because it shows the steps but I'm unsure about one of them. It might be a dumb question, but here goes:(adsbygoogle = window.adsbygoogle || []).push({});

It's for calculating [tex]\frac{d<p>}{dt}[/tex] Using the momentum operator we have:

[tex]\frac{d}{dt}<p> = -i\hbar \int_{-\infty}^{+\infty} \frac{\partial}{\partial t} (\Psi^* \frac{\partial \Psi}{\partial x})dx[/tex]

then I'm not entirely sure how they get the next step:

[tex]= -i\hbar \int_{-\infty}^{+\infty} [\frac{\partial}{\partial t}\Psi^* \frac{\partial \Psi}{\partial x} + \Psi^*\frac{\partial}{\partial x}(\frac{\partial\Psi}{\partial t})]dx[/tex]

I know this is probably just some fundamental rule of integration. But I put the whole equations up anyway. Please just explain it to me. If it is just a rule I have to memorize would you possibly be able to point me somewhere that explains how they derive it?

Thank you.

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# Homework Help: Integration help (expectation value)

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